Electrical signaling apparatus.



No. 775,390. PATENTED NOV. 22, 1904.

s. OABOT.

ELECTRICAL SIGNALING APPARATUS.

APPLICATION FILED MAR. 23, 1904.

no MODEL. 3SHEBTS-8HBET 1.

PATBNTED NOV. 22, 1904.

S. GABOT. ELECTRICAL SIGNALING APPARATUS.

APPLICATION FILED M11123, 1904.

3 SHEETS-SHEET 2.

NO MODEL.

IA 55555. I

PATENTEI) NOV. 22, 1904.

S. OABOT.

ELECTRICAL SIGNALING APPARATUS.

APPLICATION FILED MAR. 23, 1904.

3 SHEETS-SHEET 3.

N0 MODEL.

# Wil l DY.

4 AZ: xfl mpy UNITED STATES Patented November 22, 1904.

SE'WALL GABOT, OF BROOKLINE, MASSACHUSETTS.

ELECTRICAL SIGNALING APPARATUS.

SPECIFICATION forming part of Letters Patent No. 775,890, dated November22, 1904.

Application filed March 23, 1904.

1'0 (ML w/tmn it may concern:

Be it known that 1, SEWALL CABOT, a citizen of the United States, and aresident of Brookline, in the county of Norfolk and State ofMassachusetts, have invented new and useful Improvements in ElectricalSignaling Apparatus, of which the following is a specification.

My invention relates generally to telegraphy and telegraphic signaling;and it consists, broadly, of an apparatus whereby, among other possibleuses, reciprocal conditions in a line between sending and receivingstations may be determined automatically by the operator at either endof the line.

More particularly, my invention resides in telegraphic orelectrically-controlled apparatus by which an electric switch orconceivably any movable or changeable mechanical or electromechanicalapparatus may be automatically operated by electric impulses.

Further and in a more specific aspect, my invention consists, first, inan electromechanical attachment applicable to a telegraphic repeater ofa well-known construction, this apparatus having special utility as ameans of automatic communication with and control over automaticelectric switch-operating apparatus, and, second, an automaticswitch-controlling apparatus adapted to be used in connection with atelegraphic repeater.

The salient features of my invention, hereinafter to be described andclaimed, are conceivably susceptible of a number of applications and usein the manifold developments of electric signaling. I show and describe,however, an embodiment of my invention and improvements particularly asapplied to and as a modification of a well-known and heretofore quitefrequently-used telegraphic repeater, which is called the l/Voodsbutton-repeater, and for purposes of elucidation I have shown, in

Figure 1, hereto annexed, a diagrammatic representation of this form ofrepeater reduced electrically to its simplest terms. In Fig. 2 I haveshown diagrammatically one step in my modification of or addition to therepeater typically illustrated in Fig. 1. In

Fig. 3 1 illustrate diagrammatically a form of Serial No. 199,561. (Nomodel.)

that feature of my invention which relates to automaticswitch-controlling apparatus, and in Fig. 4 I show the automaticswitch-controlling apparatus of Fig.. 3 applied to the modified repeaterarrangement illustrated in Fig. 2. In Fig. 5 I have illustrated indiagram a modification of the apparatus shown in Fig. 3, thismodification operating, however, according to the same method andprinciple as that which characterizes theapparatus shown in Fig. 4.

Referring now to Fig. 1, which shows in diagram a simple form of IVoodsbutton-repeater, A is the key of one station, and B the key of another,each key connected and grounded in an ordinary manner. The linewire 1extends from station A to the energizing-coil of the electromagnet a andthence to the post of the armature I). The line 2 extends from station Bto the energizing-coil of electromagnet 1/ and thence to the post of thearmature a of the electromagnet a. Retracting-springs (1' and normallywithdraw the armatures (f and If from the electromagnets a and 7).Repeater-contacts (1* and 6* are mounted in such position and adjustmentthat when electromagnet at or b is energized the corresponding armatureis drawn into electrical connection with the repeater-contact (0* or If,as the case may be. From the armatures a and If, respectively, wires aand U extend to and are connected with switchcontacts a and 9',respectively, and from the repeater-contacts a and 6" wires (L7 11extend to and are connected with wires (1 l), which in turn connect withthe switch-contacts q and 1), respectively. Batteries M M, connectedwith wires and b and grounded at G G, respectively,supply the electricalenergy for the repeating-station and serve also as the line-batteries. Aswitch S under the manual control of an attendant serves to connectcontacts p r or q 8, according to the position to which the switch S ismoved. If station Abe regarded as the sending-station, station B keepsits key closed, and interruptions of keycontact at station A givesignals to be repeated from line 1 to line 2, the switch S being in theposition shown in full lines in Fig- 1, where contacts n and oareconnected there.

by. Assume that while A is sending a message B opens his key as a signalthat he wishes to send to A. When A next closes his key, his relay at awill operate, the circuit being established from ground through A,wire 1. armature '6 wire 6 contacts 1' and p, and switch S, wire 6, wireZ2 to battery M, and thence again to ground G; but relay Z) will fail tooperate, the circuit at key B being open. The attendant at therepeating-station noting the relay 6 fails to operate recognizes this asa signal to change the condition of the line, so that station B may sendto station A. This attendant then removes the short circuit from thecontact points 0 r, and as these points are now open the operator at Aon closing his key finds the circuit open and is made aware of the factthat station B wishes to send to him. He then closes his key to receivesignals, and in the meantime the attendant at the repeater-station hasplaced the shortcircuiting switch S in its dotted-line position acrossthe points 9 s, so. that the operator at station B when he closes hiskey finds the circuit closed and may proceed to send a message tostation A. Both the line-relays a 6 again work in unison, and thiscondition continues until the operator at A desires to send a message toB and opens his key at a time when the key at B is closed. The foregoingis a description of the construction and operation of the old andwell-known Woods button-repeater.

Passing now to Fig. 2, I therein show in diagram the first step in themodification of the Woods button-repeater toward that embodiment of myinvention which consists in automatic switch operating contrivances,whereby the services of the attendant at a relay-station may bedispensed with and the operators at stations A and B may controlconditions at the repeating-station to suit themselves. At the back ofthe armatures a and b I secure back contacts a and 6 which are separatedfrom the armatures themselves by insulation a I). Fixed contacts a andI) are connected with ground G G and the armature-pieces a b areconnected by wires a I) to the local-circuit wirings of the relaymagnetC and battery i The coil of the magnet C is connected with branch wires0 0 running from wires 6 and a, respectively. Resistances 0 0 areconnected with wires 6 a, respectively, and meet in a connection 0 tothe battery M which at its other pole is connected to ground G*. Iffound expedient, these resistances may be relatively adjusted ordiversified. The armature c of relay C is provided with the usualretractile spring 0 and cooperates with a fixed contact-piece 0 which isgrounded at G and from the armature 0 there extends the wire marked w.

So far as the diagram of Fig. 2 goes to show the apparatus associatedwith the relay C is of no definite specific utility.

It is shown in this connection in order to illustrate more clearly itsrelation to the relay apparatus of the repeating-station. In Fig. 2 alsothe button-switch arrangements are omitted, and it is for the presentleft to the imagination to supply an automatic switch-operating devicewhich shall'be controlled by the operation of relay C and its attendantmechanism. For the sake of clearness of illustration that portion of theapparatus shown in Fig. 2 which distinguishes it from the apparatus ofFig. 1 is shown in heavy lines. Supposing now that the operator atstation A is sendingja message to station B and the determining switchor equivalent apparatus connects contacts 10 1", thus maintaining theline in condition to send messages from A to B, it has been shown inconnection with Fig. 1 that if the operator at station B breaks hiscircuit while the sending-key at A is closed the'synchronism of therelays a Z) is interrupted, relay 6 failing to act in unison with relay(4. With the apparatus illustrated in Fig. 2 when the operator at Bbreaks his key connection in this manner relay-magnet at b isdeenergized and its retractile spring draws the back contact 6 intoclosure with the fixed contact 6 This grounds the wire I) at G3, and thecurrent flows from battery M through both resistances 0 0 Wires 0*,ciand 6 thus energizing the relay-magnet C, attracting the armature 0into contact with the fixed piece 0 and grounding the wire :0 at Gr Onlyunder these conditions or under the reciprocal conditions when B is thesender and A the receiver will the relay-magnet C be actuated to groundthe wire 00, because under any other conditions either no current at allflows over the wires a b or else there is ,no difference in potentialbetween the junctions of wire 0 0 to the circuit of battery M Thus onlywhen the sender7s key is closed and the receiver opens his key-circuitwill the circuit formed by the wire m be closed. In Fig. 2 I have showna dotted square (marked Y) embracing the button-switch contacts 19 q r sand have illustrated the wire :v as terminating in this dot-ted squareY. If now it be assumed that the square Y represents an automaticswitch-operating mechanism, of which the action shall be directed'anddetermined by the grounding of the wire 00, it is apparent that thereceiver, either A or B, may at his option whenever the circuit isclosed determine the conditions at the repeating-station, which shallautomatically cause a reversal of position ofthe circuit-establishingswitch, and thus place the receiver at B into position to operate as asender to A, or vice versa.

, In Fig. 3 I show diagrammatically an apparatus which fulfils theautomatic conditions heretofore assumed with respect to the dottedsquare Y of Fig. 2. For the sake of avoidingconfusion I have shown inFig. 3 only the terminus ofthe wire w and the contact-points springs a asupplying the source of energy for one movement of the switch, while thecoil of the electromagnet F supplies the energy for the reversemovement- The elec.

tromagnet E, which I term the operatingmagnet, is provided with twocoils which are dili'erentially wound, one of them (connected with wirea) being in series with the coil of electromagnet F, the other(connected with wire 6) being connected with armature-operated contactspresently to be described. A third electromagnet, D, which 1 term thepreparatory magnet, is also provided with two coils or sections of coil;but these are wound so that whether one or both of the coils beenergized the magnet D will attract its armature. The coil '7 isgrounded at G, while the coil 8 is connected at one end with wire 6 andat the other with the battery M Resistances 9 and 10 provide means forobtaining the necessary balance between magnetic moments of theditterential coils of magnet E and otherwise adjusting magnetic momentsto their proper value with relation to the battery strength employed.The wiring of this system is as follows: Beginning with the wire :0,this wire is connected with switch-arm (Z which is drawn by theretractile spring (1 against a stop (Z From this stop extends the wire3, which is connected to the switch-arm e the said switch-arm beingdrawn against the stop e by retractile spring 6. Connected also with theswitcharm (5 is the wire 4, which forms one section of the ditt'erentialcoiling of the operatingmagnet E and extends therefrom to the coil ofmagnet F and thence to battery M", which is grounded at (at at itsopposite pole. The armature e of the magnet E is connected by wire 7 toone of the coils on magnet D and thence to ground G. The armature c ofthe magnet E is connected by wire 5 and resistance-coil 10 with batteryM The switcharm is connected by wire 6 with the second coil of magnet Eand thence to the armature (Z of magnet D. The wire 8 connects with wire6 at one terminus and extends thence through the second coil of magnet Dand thence to resistance-coil 9 and battery M Now suppose that wire a begrounded. This at once closes circuit through (Z wire 3, wire 4, batteryM to ground 6". Coils of wire 4: around magnets E and Fenergize thosemagnets which attract their respective armatures. The armatures 5 S ofmagnet F are drawn into contact, respectively, with points q and s. Theclosure of the circuit from 41' through .1noved from wire 11*.

ed again.

battery M to ground at G has energized magnet E, and the armatures v care drawn into contact with the switch-arms c Tracing the circuitsthrough these contacts, it will be seen that the closure from ground (.ithrough coil and wire T, armature e, switch-arm (2 wire et to battery Mand ground G is established. This closure of circuit-contacts, however,is for the present ineli'ective to energize magnet D, becausev theground of wire it remains unbroken and the resistance from wire .11 toground is when comparedwith the resistance of the coil of wire 7 onmagnet D practicallym'l. Now let the ground be re- This diverts thecurrent through the circuit already closed by contact from ground Gthrough wire 7, armature 0, arm 0 wire t to battery M and the armature(Z of magnet D is attracted and comes in contact with and removes thearm (Z from its stop-contact (1. At this stage of the cycle all themagnets D, E, and F are energized and their armatures consequentlylocked in position. Vith the apparatus in this condition suppose thewire :1: to be groundlts connection with wire 3 is broken at the point(Z but a circuit is now closed from wire :v through arm (1", armature(Z, wire 6, through the neutralizing-coil of magnet E, switch-arm (3S,armature wire 5 to battery M and ground G. The simultaneous closure ofcircuit through both coils of the magnet E throws that magnet out ofaction, the said coils being differentially wound with respect to theforce and polarity of their magnetism, and the retractile springs e aassert themselves, and contacts between the armatures d-e and theswitch-arms e e are broken. Magnet E thus at this stage of the cycleperforms the function of a releasingmagnet, in that it breaks thecircuit of the coil of magnet F, thereto fore conserved in its conditionof circuit-closure by the contacts operated by magnet E. The coil of themag net F is thus thrown out of circuit, the elesure-conserving circuitbeing broken between a and e and the original circuit not yet beingclosed between d" and d, as magnet D is still energized and theswitch-arm d is held from its contact-point (Z The relaxation of energyin the magnet F gives the springs .s" an opportunity to swing theswitch-arms S S over against the contacts 3) 1*, respectively. Nowsuppose the wire 11' to be once more removed from ground. The circuitfrom m through (1 (1, wire 6 to switch-arm c has been previously brokenbetween a and armature Likewise the circuit from :1 through d, d, wire6, wire 8 to battery M", and ground G is now broken by the removal ofground from wire .1. The coil of wire 7 has previously had its circuitopened between armature e and switch-arm c and the magnet D is thus leftwithout energy, and its armature (Z' is pulled by the spring (Z againstthe stop 0Z Spring 0? draws arm cl against'stop (Z and the apparatus isrestored to the condition in which we'first found it.

Recapitulating, the cycle of operations of the apparatus shown in Fig. 3(assuming the initial condition of open circuit and inertness of themagnets D, E, and F) is as follows:

(1) Ground wire at. This energizes magnets E and F in series, and magnetF throws the switch-arms S S By closure of circuit of one of its coilsmagnet D is ready to act, but remains inactive because of the highresistance of its coil and the relatively low resistance to groundthrough wire w.

(2) Remove the groundfrom wire 00. Magnets E and F remain energized, anda coil of magnet D is energized. The movement of the armature of magnetD cuts off the wire w from its previous connection to the operating-coilof magnet E and connects it to the neutralizingcoil of magnet E andholding-coil of magnet D. Magnets E and F are now closed through thecoil of magnet D to ground.

(3) Ground wire :11 again. The second or neutralizing coil of the twodifferential coils on the magnet E is now in closed circuit, and magnetE ceases to operate. This breaks the connections established through thecoil of magnet F, and that ceases to operate. Magnet D remains energizedthrough its own armature connections and holding-coil.

(4) Remove the ground from m. This breaks the last connection throughthe coil of magnet D, which ceases to operate, and its armatures areretracted to their original position.

It is clear, therefore, that whatever condition is determined at themagnet F by a grounding of wire a that condition is preservedirrespective of the removal of ground from wire at until a subsequentsuccessive grounding of w.

The foregoing description of cycle of operations demonstrates thefollowing: that magnet D operates one way or the other only when thecontrol-circuit of the control-line (wire w) is broken and also thatmagnet E operates one way or the other only when the control-circuit ofthe controleline (wire 00) is closed, and, moreover, that the operationof magnet D, whether it be energized or deenergized, upon the opening ofthe circuit of wire mis preparatory to and determines the.

action of magnet E upon a subsequent closing of the circuit ac. Thefunction of magnet D is therefore preparatory, and at the same time theaction of magnet E has a reciprocal effect upon the magnet D, so thattheserial or cycle operation of the magnets in this apparatus ispredetermined. the apparatus as a whole, however, magnet E performs thefunctions of an operating relay or magnet, in that when by the activityof one of its coils it is energized it serves to close and maintain thecircuit necessary to hold the switch-armatures against their retracting-In its relation to effect on the switch-arms and separate mag-- net F beeliminated. The continuance of magnetism in one coil of magnet E isneces-' sary to hold the switch-arms, whether the magnet F be used or Ealone. It is when the switch-arms are released that the function ofoperating-magnet E as a releasing-magnet comes into prominence. In thecycle operationl of the apparatus the magnet E at one stage of the cycleperforms the function of holding the switch-arms in the specificapparatusshown by preserving the closure of circuit through the coil ofmagnet F and at this stage is effective. to conserve the condition inthe magnet F, which was suspended by the previous circuit-closure of thecontrol-line. Ifthis condition is to be preserved in the coil of magnetF, it is obviously advisable to provide circuit conserving mechanismwhich shall operate independently of the closure of the control-linecircuit, and thus be unaffected while that circuit is open. In Fig. 4: Ihave shown in diagram the entire assembled apparatus heretoforedescribed by instalments in connection with Figs. 1, 2, and 3. The wire00 serves as the connection between the automatic switch-operatingmechanism and the determining-relay 0. Referring back to Fig. 2 and thedescription relating thereto, it will be remembered that thedetermining-relay C operates to close the circuit of wire 00 only whenthe receiving-station key is opened at a time when the sending-stationkey is closed, and it will be remembered also in connection with thedescription of Fig. 1 that when the button-switch is closed betweencontacts 10 and r A is a sending-station and B is a receiving-stationand that when the said switch closes contacts q and s B is the sendingand A the receiving station. order to enable B to ground the wire 00, itis essential that the button-switch is in such position that B is areceiving-station. A cannot operate the relay C until the button-switchis reversed and A is the receiving-station.

Referring again to Fig. 2, suppose the switch closes points 10 r and thereceiver B while the key A is closed opens his key and operates therelay 0, and that then, either by an attendant or by automatic means,the connection between points 12 r is broken and that between q and s isclosed. The circuit through the coil of magnet C' is thus at oncebroken, because the circuit from A, through wire 1, armature 6 wire Z2wire I), to battery M and ground G is broken at the points 19 r;relaymagnet loses its energy, and the armature a is drawn against thefixed contact (0 and the current is established from G through contact aback contact a wire a, resistance ally shifts the switch-contact, sothat the connection between 1) and 0- is broken and that between (1 andis established, the armatureswitches S and S being connected by wire 5This reversal of the automatic button-switch instantly throws the magnetC out of action and breaks the ground of wire (B. By the automaticoperation of the switch the complete cycle of this apparatus is asfollows, starting with the condition where A is the sending and B is thereceiving station, magnet F being inert and the button-switchcontacts 1) 1' being connected.

(1) Receiver B when the key at A is closed open his key. Magnet 0 isenergized, and the circuit of wire m is closed to ground. Magnets E andF are energized in series, and switches S S shift the closure from g)'2' to q s, and a coil of magnet D is connected to contacts 0 butremains inert by reason of its high resistance relatively to the circuitthrough wire a; to ground.

(2) The shifting of the switch-arms S S automatically opens the circuitof wire Magnets E and F remain energized. Magnet D is energized. Themovement of the armature of magnet D cuts off the direct connection ofwire :r from the coil of magnet E; but magnets E and F remain energizedthrough the circuit-closure of the wires through the coils of magnet Dto ground.

(3) The operator at station A, which is now the receiving-station,interrupts by opening his key while the key at B is closed. This closesthe circuit of wire a: to ground by the operation of magnet C. Thesecond of the two differential coils on magnet E is closed. Magnet Ebecomes inert, and the coil of F is cut out. The switch S S is thrown inthe reversed direction by the retractile springs 8' s and this operationagain automatically removes the ground from (at) Upon the automaticopening of the circuit of wire in the current in the coil of magnet D isinterrupted and the armature of magnet D responds to the retractilespring (Z and the cycle is complete, the apparatus being left in thecondition first supposed, whereA is the sending-station and B is thereceiving-station.

WVith respect to the automatic switch-operating mechanism the circuit ofthe wire it is the control-circuit, and it is clear that whatevercondition is determined in the switchoperating magnet by thecircuit-closure of the control-line that condition is preservedirrespective of the circuit-opening of the control-line until asubsequent successive circuitclosure of the control-line, and, moreover,whatever condition is determined at the switchoperating magnet by aclosure of the controlcircuit the resulting operation of the switclbmagnet automatically opens the control-circuit.

It will be obvious that'a control-line circuit and its determiningapparatus substantially like that embodied in the relay-umgnetC and itsattendant devices may be utilized to actuate or initiate the operationof many conceivable electrical, mechanical, or electromechanicalapparatus, and it will also be obvious that the combination ofelectromechanical devices such as illustrated in Fig. 3 may be employedusefully in situations which differ speeifically from the one hereinadopted to illustrate the operation and utility of this apparatus.

I have shown in Fig. 5 a modification of the apparatus of Fig. 3. Itwill have been observed that the action of electromagnets E and F is atall times simultaneous. It is therefore quite feasible to make onemagnet do the work of two by using the differentially-wound magnet Ewith a combination of switches actuated by the armatures which performthe functions of the switches S S on one hand and the circuit closingand opening functions of the armatures a and on the other. In this formof apparatus the switch-armatures S S are, in common with the armaturea, placed within the effective field of force of the magnet E and are,as before, connected by a wire a. The retracting-springs s or the forceof the magnet E is efiective to draw the armatures S S in one directionor the other. This condensed arrangement, whereby one of the magnetsshown in Fig. 4 is dispensed with, may be substituted for the completeapparatus shown in Fig. 4, but will operate upon exactly the sameprinciple. However, for reasons connected with the possibilities anddifiiculties of adjustment of relay apparatus I prefer at present thearrangement shown in Fig. 3, where the switch-magnet and theoperatingmagnet are separate pieces of apparatus. Theoretically the onlydifference between the apparatus in Fig. 3 and the modification in Fig.5 is that in that of Fig. 5 the magnet E is made to perform the doublefunction of switch and operating magnets, the functions, however,remaining as distinct as when the apparatus of Fig. 3 is employed.

That I claim is 1. The combination of a control-line, anoperating-electromagnet, a preparatory electromagnet, armatures for thesaid magnets, closure-contacts, electric connections between thecontrol-line and the coils of the said electromagnets and between therespective coils of the said electromagnets whereof the closure-contactsare reciprocally controlled by the said armatures.

2.. The combination with a control-line, an operating-electromagnethaving differential coils, a preparatory elcctromagnet, armatures IIOfor the said magnets, closure-contacts, electric connections between thecontrol-line and the coils of the said electromagnets and between therespective coils of the said eleotromagnets whereof the closure-contactsare reciprocally controlled by the said armatures.

3. The combination of a control-line, an operating-electromagnet havingdifferential coils, a preparatory electromagnet having twomagnetically-similar coils, armatures for the said magnets, closure-contacts, electric connections between the control-line and the coils ofsaid electromagnets and between the respective coils of the saidelectromagnets whereof the closure-contacts are reciprocally controlledby the said armatures. V

4. The combination of a control-line, an operating-electromagnet havingtwo difierentially-wound coils, a preparatory electromagnet having twosimilarly-wound coils, armatures for the magnets, closure-contacts,circuit connections as follows: one from the control-line through onecoil of the operatingmagnet; one from one coil of the operatingmagnetthrough one coil of the preparatory magnet; one from the control-linethrough the other coil of the operating-magnet; and one from thecontrol-line through the other coil of the preparatory magnet, theclosurecontacts of these circuit connections being controlled by thereciprocal action of the magnetarmatures.

5. The combination of a control-line, an operating-electromagnet and apreparatory electromagnet, armatures for the said magnets, electriccircuits inclusive of the controlline and coils of said magnets, andclosure-contacts therefor controlled by the said armatures to preservewhatever conditions a change in the electrical state (such ascircuit-closure) of the control-line determines in the operating-magnet,irrespective of a counterchange in said electrical state, until asubsequent successive resumption of the original determining electricalstate by the control-line.

6. The combination of a control-line, an

operating-electromagnet having differential coils, a preparatoryelectromagnet, armatures for the said magnets, electric circuitsinclusive of the control-line and the coils of said magnets, andclosure-contacts therefor controlled by the said armatures to preservewhatever condition a change in the electrical state (such ascircuit-closure) of the control-line determines in the operating-magnet,irrespective of a counterchange in the said electrical state, until asubsequent successive resumption of the original determining electricalstate by the control-line. V

7. The combination of a control-line, an operating-electromagnet havingdifferential coils, a preparatory electromagnet having twomagnetically-similar coils, armatures for the said magnets, electriccircuits inclusive of the control-line and said magnet-coils, andclosuretures for the magnets, electric circuits as follows: one from thecontrol-line through one coil of the operating-magnet; one from one coilof the operating-magnet through one coil of the preparatory magnet; onefrom the control-line through the other coil of the operating-magnet;and one from the control-line through the other coil of the preparatorymagnet; and closure-contacts for the said circuits controlled by thesaid armatures to preserve whatever condition a change in the electricalstate (such as circuit-closures) of the controlline determines in theoperating-magnet, irrespective of a counterchange in said electricalstate, until a subsequent successive resumption of the originaldetermining electrical state by the control-line.

9. The combination with a telegraphic repeating apparatus of thecharacter described, of an electromagnet, a battery or its equivalent,electric connections between the battery and the movable parts of therepeating apparatus, and closure-contacts controlled by said movableparts and between the battery and the said electromagnet, the latterconnections electrically inert when the said movable parts of therepeating apparatus move in unison and electrically active when saidunison is interrupted, and means actuated by the operation of the saidelectromagnet for automatically throwing the determining-switch of therepeating apparatus.

10. The combination with a telegraphic repeating apparatus of thecharacter described, of a relay, electrical connections between thecoils thereof to a source of electrical energy and the movable parts ofthe reciprocally-arranged instruments of the repeating appara: tus, saidelectrical connections constituting the means whereby the said relay isenergized when the receiver-key is opened and the sender-key is closed.

11. In combination with a telegraphic repeating apparatus of thecharacter described modified by having its repeater-switch adapted toelectromagnetic control, a relay having its coil electrically connectedto the movable parts of the reciprocally-arranged instruments of therepeating apparatus and to a source of electrical energy, the said relaymagnet-coil electrically inert when the said instruments act in unisonand energized when this unison is broken, and a control-line where- IIOof the circuit-closure is determined by the operation of said relay, anoperating-electromagnet therefor, a preparatory magnet, armatures forthe said magnets, electric circuits inclusive of the control-line andthe coils of the said magnets, and closure-contacts therefor controlledreciprocally by the armature of the said magnets.

12. .In combination with a telegraphic repeating apparatus of thecharacter described modified by having its repeater-switch adapted toelectromagnetic cont-r01, a relay having its coil electrically connectedto the movable parts of the reciprocallyarranged instruments of therepeating apparatus and to a source of electrical energy the saidrelaymagnet coil electrically inert when said instruments act in unisonand energized when this unison is broken, and a controlline whereof thecircuit-closure is determined by the operation of said relay, anoperating-electromagnet therefor, a preparatory magnet, armatures forthe said magnets, electric circuits inclusive of the control-line andthe coils of the said magnets, and closure-contacts therefor controlledby the said armatures to preserve whatever condition a change in theelectrical state (such as circuit-closure) of the control-linedetermines in the switch-operating magnet, irrespective of acounterchange in said electrical state, until a subsequent successiveresumption of the original determin ing electrical state by thecontrol-line.

13. In combination with a telegraphic repeating apparatus of thecharacter described modified by having its repeater-switch adapted toelectromagnetic control, a relay having its coil electrically connectedto the movable parts of the reciprocally-arranged inst-ruments of therepeating apparatus and to a source of electrical energy, the saidrelay-coil electrically inert when the said instruments act in unison,and energized when this unison is broken, and a control-line whereof thecircuit closure is determined by the operation of said relay, anoperatingelectromagnet thereforhavingtwodifferentiallywound coils, apreparatory electromagnet having two similarly-wound coils, armaturesfor the said magnets, circuit connections as follows: one from thecontrol-line through one coil of the switch-operating magnet; one fromone coil of the switch-operating magnet through one coil of thepreparatory magnet; one from the control-line through the other coil ofthe switch-operating magnet; and one from the control-line through theothercoil of the preparatory magnet, the closure-contacts of thesecircuit connections being controlled by the reciprocal action of themagnet-armatures.

H. In combination with a telegraphic repeating apparatus of thecharacter described modified by having its repeater-switch adapted toelectromagnetic control, a relay having its coils electrically connectedto the movable parts of the reciprocally-arranged instruments of therepeating apparatus and to a source of electrical energy the saidrelay-coil electrically inert when the said instruments act in unison,and energized when this unison is broken, and a control-line whereof thecircuitclosure is determined by the operation of said relay, anoperatingelectromagnet therefor having two ditferentially-wound coils, apreparatory electromagnet having two similarlywound coils, armatures forthe said magnets, circuit connections as follows: one from thecontrol-line through one coil of the switchoperating magnet; one fromone coil of the switch-operating magnet through one coil of thepreparatory magnet; one from the controlline through the other coil ofthe switch-operating magnet; and one from the control-line through theother coil of the preparatory magnet; the closure-contacts of thesecircuit connections being controlled by the reciprocal action of themagnet-armatures to preserve relative conditions a change in theelectrical condition (such as circuit-closure) of the control-linedetermines in the switch-operating magnet irrespective of acounterchange in said electrical state until a subsequent resumption ofthe original determining electrical state by the control-line.

15. In combination, two lines; two switches, one in each line; tworelays one for each line, each adapted to be actuated by its respectiveline to operate the other line; a switch for controlling said relays toadapt either line to send and the other to receive signals; a pair ofopposed circuits, each controlled by one of said relays; a third relaycontrolled by the pair of opposed circuits; a circuit controlled by thethird relay for operating the relay-con trolling switch, and means tomaintain the third relayinert when under the joint control of saidopposed circuits and for causing said relay to operate the circuit ofthe relay-controlling switch and reverse the conditions of the two lineswhen either of the opposed circuits is operated to the exclusion of theother. 16. In combination, two lines; two switches, one in each line;two relays, one for each line,- each adapted to be actuated by itsrespective line to operate the other line; a switch for controlling saidrelays to adapt either line to send and the other to receive signals; apair of opposed circuits each controlled by one of said relays; a thirdrelay controlled by the pair of opposed circuits; at control-circuitoperated by the third relay; means to maintain the third relay inertwhen under the joint control of said opposed circuits and for causingsaid relay to operate the control-circuit and reverse the conditions ofthe two lines when either of the opposed circuits is operated to theexclusion of the other, and means cooperating with said control-circuitfor causing alternate operations of said control-circuit to shift theswitch in one direction, and the other operations of saidcontrol-circuit to shift the switch in the opposite direction.

17. In combination, two lines; two switches, one in each line; tworelays, one for each line, each adapted to be actuated by its respectiveline to operate the other line; a switch for controlling said relays toadapt either line to send and the other to receive signals; a pair ofopposed circuits, each controlled by one of said relays; a shuntconnecting said opposed circuits; a relay in said shunt; a circuitcontrolled by the shunt-relay for operating the relay-controllingswitch; and resistances in the opposed circuits for causing saidshunt-relay to operate the circuit of the relay-controlling switch andreverse the conditions of the twolines when either of the opposedcircuits is operated to the exclusion of the other.

18. In combination, two lines; two switches, one in each line; tworelays, one for each line, each adapted to be actuated by its respectiveline to operate the other line; a switch for conrelay-controllingswitch, said third relay being inert when under the joint control ofsaid opposed circuits and actuated by the operation of either of saidopposed circuits to the exclusion of the other to operate the control--circuit of the electromechanical apparatus and reverse therelay-controlling switch.

Signed by me at Boston, Massachusetts, this 29th day of February, 1904.

SEWALL CABOT.

Witnesses ARTHUR F. RANDALL, JOSEPH T. BRENNAN.

